1 =======
2 Locking
3 =======
4
5 This file explains the locking and exclusion scheme used in the PCCARD
6 and PCMCIA subsystems.
7
8
9 A) Overview, Locking Hierarchy:
10 ===============================
11
12 pcmcia_socket_list_rwsem
13 - protects only the list of sockets
14
15 - skt_mutex
16 - serializes card insert / ejection
17
18 - ops_mutex
19 - serializes socket operation
20
21
22 B) Exclusion
23 ============
24
25 The following functions and callbacks to struct pcmcia_socket must
26 be called with "skt_mutex" held::
27
28 socket_detect_change()
29 send_event()
30 socket_reset()
31 socket_shutdown()
32 socket_setup()
33 socket_remove()
34 socket_insert()
35 socket_early_resume()
36 socket_late_resume()
37 socket_resume()
38 socket_suspend()
39
40 struct pcmcia_callback *callback
41
42 The following functions and callbacks to struct pcmcia_socket must
43 be called with "ops_mutex" held::
44
45 socket_reset()
46 socket_setup()
47
48 struct pccard_operations *ops
49 struct pccard_resource_ops *resource_ops;
50
51 Note that send_event() and `struct pcmcia_callback *callback` must not be
52 called with "ops_mutex" held.
53
54
55 C) Protection
56 =============
57
58 1. Global Data:
59 ---------------
60 struct list_head pcmcia_socket_list;
61
62 protected by pcmcia_socket_list_rwsem;
63
64
65 2. Per-Socket Data:
66 -------------------
67 The resource_ops and their data are protected by ops_mutex.
68
69 The "main" struct pcmcia_socket is protected as follows (read-only fields
70 or single-use fields not mentioned):
71
72 - by pcmcia_socket_list_rwsem::
73
74 struct list_head socket_list;
75
76 - by thread_lock::
77
78 unsigned int thread_events;
79
80 - by skt_mutex::
81
82 u_int suspended_state;
83 void (*tune_bridge);
84 struct pcmcia_callback *callback;
85 int resume_status;
86
87 - by ops_mutex::
88
89 socket_state_t socket;
90 u_int state;
91 u_short lock_count;
92 pccard_mem_map cis_mem;
93 void __iomem *cis_virt;
94 struct { } irq;
95 io_window_t io[];
96 pccard_mem_map win[];
97 struct list_head cis_cache;
98 size_t fake_cis_len;
99 u8 *fake_cis;
100 u_int irq_mask;
101 void (*zoom_video);
102 int (*power_hook);
103 u8 resource...;
104 struct list_head devices_list;
105 u8 device_count;
106 struct pcmcia_state;
107
108
109 3. Per PCMCIA-device Data:
110 --------------------------
111
112 The "main" struct pcmcia_device is protected as follows (read-only fields
113 or single-use fields not mentioned):
114
115
116 - by pcmcia_socket->ops_mutex::
117
118 struct list_head socket_device_list;
119 struct config_t *function_config;
120 u16 _irq:1;
121 u16 _io:1;
122 u16 _win:4;
123 u16 _locked:1;
124 u16 allow_func_id_match:1;
125 u16 suspended:1;
126 u16 _removed:1;
127
128 - by the PCMCIA driver::
129
130 io_req_t io;
131 irq_req_t irq;
132 config_req_t conf;
133 window_handle_t win;
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